The field of the present invention is articulated tricycles and the structure and drive thereof.
Articulated or swingable tricycles have been developed such as illustrated in FIG. 9. In such tricycles, a front body 10 includes a front wheel 12 which is steerable by means of the conventional handlebars 14, a seat 16 and the requisite frame structure to support same. A rear body 18 includes two rear wheels 20, an engine 22 and a power train 24. The engine 22 is coupled to an axle of the rear wheel 20 through the power train 24 by a conventional chain and sprocket mechanism. The tricycle is articulated between the front body 10 and the rear body 18 such that the rear body 18 may swing in a vertical plane about a transverse axis 25 through bracket 26; and a front body 10 may roll relative to the rear body 18 and relative to the ground about a longitudinal axis through a rolling joint 28. The rolling joint includes a joint case 30 pivotally mounted to the bracket 26 and a shaft 32 extending into the joint case 30. The shaft 32 is fixed to the rear body 18. Thus, relative motion between the front body 10 and the rear body 18 may occur about the transverse axis of the bracket 26 and the longitudinal axis of the rolling joint 28. A cushion member 34 acts as a suspension mechanism between the front body 10 and the rear body 18.
The operation of such articulated tricycles is to have the front body lean or roll into a turn while the rear body remains upright with both wheels 20 remaining on the ground. The tricycle is suspended using a conventional front wheel cushion and the cushion member 34. Thus, the entire rear body 18, including the engine 22, the power train 24, and the rear wheels 20, acts as unsprung weight. Because of the nature of this arrangement, a substantial percentage of the mass of the tricycle is unsprung. Additionally, the length of the rear body 18 is generally determined by the space required for the engine 22, the power train 24 and the wheels 20. The effective length creates a substantial moment arm. Thus, the unsprung mass for such articulated tricycles has a relatively high inertia and moment of inertia. This detracts from the ride of the vehicle and makes the design of an optimum cushioning system difficult.
Another articulated or swingable tricycle having a reduced unsprung mass by having an engine mounted on the front body of the vehicle is illustrated in copending U.S. Patent Application to Mita, entitled Articulated Tricycle Ser. No. 472,083 filed Mar. 4, 1983. The Mita application is incorporated herein by reference.